The worldwide demand for energy is growing. The US Energy Information Administration reported that in 2006, the world energy consumption was 500 exojoules=500×1018 J. In order for all people in the world to be brought up to the standard of living of the industrialized countries, worldwide production of energy would need to increase by a factor of four. In 2006, energy was approximately 10% of the total world gross domestic product. The cost of energy is a significant fraction of the GNP of developed countries and the lack of energy is a major obstacle to improving the standard of living for people in underdeveloped countries.
Currently, approximately 86% of the world's energy comes from fossil fuels, coal, oil, and natural gas. Even if there was an unlimited supply, the combustion of fossil fuels produces unacceptable levels of greenhouse gasses for example carbon dioxide. New forms of combustible fuels such as fuel from algae will also produce greenhouse gasses and biofuels such as ethanol have the added disadvantage that a source of food is being converted into fuel. One promising new technology uses hydrogen to produce “green” energy without producing greenhouse gasses. Several technological hurdles including improved methods to produce and store hydrogen must be overcome before the hydrogen economy becomes a reality.
One promising method to more efficiently produce hydrogen involves steam electrolysis. Current steam electrolysis systems utilize steam produced by nuclear reactors to produce hydrogen more efficiently than conventional liquid electrolysis methods. Numerous scholarly articles and several patent applications including US 2011/0210010 A1 Pub. Date: Sep. 1, 2011 and WO2012084738 A3, Sep. 13, 2012, herein incorporated by reference, describe steam electrolysis systems for the production of hydrogen.
Current methods of storing hydrogen includes the use of pressure vessels for containing both liquid hydrogen as well as compressed hydrogen gas but this approach presents unacceptable safety hazards for many applications. In addition, cryogenic flasks for storing liquid hydrogen can be very expensive to build and maintain. Another hydrogen storage approach is to store hydrogen in the lattice of metal hydride materials but several technical challenges need to be solved to make this technique practical. Goals for a metal hydride storage system include the ability to extract the hydrogen at the rate of 1.5 gram per second with the metal hydride temperature less than 80 degrees C. A less than five-minute refueling time has also been established which presents a challenge to dissipate the heat that would be produced when the hydrogen is loaded into the metal lattice. See. B: F. Pinkerton and B. Wicke, “Bottling the Hydrogen genie” American Institute of Physics,—The Industrial Physicist, February/March 2004 pp 20-23.
It is well established that loading hydrogen into nickel is an exothermic reaction and that the diffusivity of hydrogen into nickel or other metal lattices increases with temperature as seen in FIG. 17 Wimmer, W. Wolf, J. Sticht, P. Saxe, C. B. Geller, R. Najafabadi, and G. A. Young, “Temperature-dependent diffusion coefficients from ab initio computations: Hydrogen, deuterium, and tritium in nickel”, Phys. Rev. B 77, 134305 (2008) herein incorporated by reference, which shows the temperature-dependent diffusion coefficients of hydrogen and its isotopes in nickel. As shown in Wimmer et al, increasing the nickel temperature from room temperature to 500° C. increases the diffusivity by 4 to 5 orders of magnitude. As shown in FIG. 17, increased temperature increases hydrogen diffusivity but this alone does not provide sufficient controls over the rate of hydrogen loading or release. See also “Diffusion of Hydrogen in Nickel” Materials Design (2009) herein incorporated by reference. One of the major issues with complex metal hydride materials, due to the reaction enthalpies involved, is thermal management during refueling. Depending on the amount of hydrogen stored and refueling times required, megawatts to half a gigawatt of heat must be handled during recharging on-board vehicular systems with metal hydrides. The present invention addresses this problem by the incorporation of a thermal management system that can include provision for recovering the energy from the exothermic reaction of hydrogen being charged into nickel.